1. Field of the Invention
The present invention relates to a method for assessing wear in a molding machine for molding a molded part by injecting and filling molten resin being melted via a heating cylinder in a mold cavity of a clamped mold through forward movement of a screw, and specifically, relates to the method for assessing wear of the screw or a heating cylinder disposed slidably in the machine.
2. Description of the Related Art
In an injection molding machine for molding a molded part via injection molding, injecting and filling of molten resin to a cavity of a mold or metering of molten resin to be injected and filled to the mold cavity are performed by moving a screw disposed in a heating cylinder back and forth or rotating the same. A surface treatment is known to be provided to such screw in the injection molding machine to form a chromium (Cr) plated layer on the surface of the screw from the viewpoint of wear resistance and seize resistance (preventing galling), and with respect to such technique, Japanese Patent Application Laid-Open Publication No. H09-302455 (patent document 1) discloses a screw having an oxide layer mainly composed of iron-chromium oxide applied on a work surface of a main body of the screw for injection molding.
According to the screw disclosed in the aforementioned patent document 1, an oxide layer mainly composed of iron-chromium oxide is formed on the work surface of a screw body in order to improve the wear resistance and seize resistance thereof, but since the screw is operated in sliding motion within a heating cylinder, it is inevitable that the wear of the surface of the screw advances during use, so that in fact, the screw had to be taken out periodically from the heating cylinder for measurement of the amount of wear and assessing whether it satisfies a predetermined condition or not, so that a complex operation was required.